Current recycling voice-coil-motor (VCM) driver circuit

Abstract

A method for driving first and second voice coil motors (VCMs) by generating a first coil current through the first VCM and routing a portion (not all) of the first coil current through the second VCM when a first VCM movement command is commanding greater movement than a second VCM movement command. A second coil current is generated through the second VCM and a portion (not all) of the second coil current is routed through the first VCM, when the first VCM movement command is commanding smaller movement than the second VCM movement command. This may reduce power consumption. Other embodiments are also described and claimed.

The invention claimed is: 
     
       1. A driver circuit for first and second voice coil motors (VCMs), comprising:
 an electrical current supply and switch network coupled to a first VCM node and a second VCM node, wherein the first VCM node is to conduct a first coil current through a first VCM, and the second VCM node is to conduct a second coil current through a second VCM; and 
 a controller to signal the electrical current supply and switch network to: 
 a) generate the first coil current and route a portion, not all, of the first coil current through the second VCM node when a commanded first VCM movement is greater than a commanded second VCM movement, and 
 b) generate the second coil current and route a portion, not all, of the second coil current through the first VCM node when the commanded first VCM movement is smaller than the commanded second VCM movement. 
 
     
     
       2. The driver circuit of  claim 1  wherein the electrical current supply and switch network comprises:
 a first variable current source to alternately produce the first coil current and the second coil current. 
 
     
     
       3. The driver circuit of  claim 2  further comprising:
 a variable dump current source to produce a dump current, wherein the variable dump current source is separately controllable by the controller in accordance with the commanded first VCM movement, such that when the commanded first VCM movement is greater than the commanded second VCM movement and said portion of the first coil current is to be routed through the second VCM node, another portion, not all, of the first coil current is routed as the dump current. 
 
     
     
       4. The driver circuit of  claim 3  wherein the variable dump current source is separately controllable by the controller in accordance with the commanded second VCM movement, such that when the commanded first VCM movement is smaller than the commanded second VCM movement and said portion of the second coil current is to be routed through the first VCM node, another portion, not all, of the second coil current is routed as the dump current. 
     
     
       5. The driver circuit of  claim 1  further comprising:
 a second variable current source, wherein the first and second variable current sources are separately controllable by the controller in accordance with the commanded first VCM movement and the commanded second VCM movement, and 
 wherein the electrical current supply and switch network is configurable into an independent mode of operation in which: 
 a) the first variable current source generates the first coil current which is routed through the first VCM node without routing a portion of the first coil current through the second VCM node, and 
 b) the second variable current source generates the second coil current which is routed through the second VCM node without routing a portion of the second coil current through the first VCM node. 
 
     
     
       6. The driver circuit of  claim 5  wherein when the commanded first VCM movement is greater than the commanded second VCM movement, and the sum of the commanded first and second VCM movements are greater than a threshold, the controller is to configure the electrical current supply and switch network into the independent mode of operation. 
     
     
       7. The driver circuit of  claim 5  wherein when the commanded first VCM movement is smaller than the commanded second VCM movement, and the sum of the commanded first and second VCM movements are greater than a threshold, the controller is to configure the electrical current supply and switch network into the independent mode of operation. 
     
     
       8. The driver circuit of  claim 1  wherein the electrical current supply and switch network is configurable into an independent mode of operation and into a recycle mode of operation,
 wherein in the independent mode of operation the first coil current is generated and routed through the first VCM node without routing a portion of the first coil current through the second VCM node, and the second coil current is generated and routed through the second VCM node without routing a portion of the second coil current through the first VCM node, 
 and wherein in the recycle mode of operation 
 a) a portion, not all, of the first coil current is routed through the second VCM node when the commanded first VCM movement is greater than the commanded second VCM movement and the commanded second VCM movement is smaller than a threshold, and 
 b) a portion, not all, of the second coil current is routed through the first VCM node when the commanded first VCM movement is smaller than the commanded second VCM movement and the commanded first VCM movement is smaller than a threshold. 
 
     
     
       9. A method for driving first and second voice coil motors (VCMs), comprising:
 receiving a first VCM movement command and a second VCM movement command; 
 generating a first coil current through a first VCM, and routing a portion, not all, of the first coil current through a second VCM when the first VCM movement command is commanding greater movement than the second VCM movement command; and 
 generating a second coil current through the second VCM and routing a portion, not all, of the second coil current through the first VCM when the first VCM movement command is commanding smaller movement than the second VCM movement command. 
 
     
     
       10. The method of  claim 9  further comprising generating a dump current in accordance with the first and second VCM movement commands, such that another portion, not all, of the generated first coil current is routed as the dump current. 
     
     
       11. The method of  claim 9  further comprising:
 a) generating the first coil current and routing the generated first coil current through the first VCM without routing a portion of the first coil current through the second VCM; and 
 b) generating the second coil current and routing the generated second coil current through the second VCM without routing a portion of the second coil current through the first VCM. 
 
     
     
       12. The method of  claim 11  wherein a) and b) are performed in response to the first VCM movement command commanding greater movement than the second VCM movement command, and the sum of the first and second VCM movement commands being greater than a threshold. 
     
     
       13. The method of  claim 11  wherein a) and b) are performed in response to the first VCM movement command commanding smaller movement than the second VCM movement command, and the sum of the first and second VCM movement commands being greater than a threshold. 
     
     
       14. A portable handheld computing device having a camera function, comprising:
 a portable handheld computing device housing having integrated therein
 an imaging sensor; 
 a multi-axis moveable imaging path element that is to change how an optical image of a scene to be captured is formed on the imaging sensor; 
 a first voice coil motor (VCM) and a second VCM coupled to the multi-axis moveable imaging path element; 
 an inertial sensor; 
 a camera optical image stabilization (OIS) controller having an input coupled to the inertial sensor, the camera OIS controller to produce a first VCM movement command and a second VCM movement command responsive to the inertial sensor; and 
 a driver circuit coupled to drive the first and second VCMs to produce first and second commanded VCM movements in response to the first and second VCM movement commands, wherein the driver circuit is to generate: 
 
 a) a first coil current through the first VCM and route a portion, not all, of the first coil current through the second VCM when the commanded first VCM movement is greater than the commanded second VCM movement, and 
 b) a second coil current through the second VCM and route a portion, not all, of the second coil current through the first VCM when the commanded first VCM movement is smaller than the commanded second VCM movement. 
 
     
     
       15. The device of  claim 14  wherein the driver circuit is to:
 a) generate the first coil current and route the generated first coil current through the first VCM without routing a portion of the first coil current through the second VCM, and 
 b) generate the second coil current and route the generated second coil current through the second VCM without routing a portion of the second coil current through the first VCM. 
 
     
     
       16. The device of  claim 15  wherein a) and b) are performed in response to the first VCM movement command commanding greater movement than the second VCM movement command, and the sum of the first and second VCM movement commands being greater than a threshold. 
     
     
       17. The device of  claim 15  wherein a) and b) are performed in response to the first VCM movement command commanding smaller movement than the second VCM movement command, and the sum of the first and second VCM movement commands being greater than a threshold.